Carbon Emissions Raising Ocean Acidity, Imperiling Food Chain

November 27, 2006
Elizabeth Kolbert , a New Yorker staff writer and former New York Times reporter who has written extensively about global warming, published a sober and terrifying piece in the Nov. 20 New Yorker. "The Darkening Sea" reports on an impact of carbon emissions that is recognized by a small circle of scientists but so far mostly overlooked in the rising public alarm about global warming: the destruction of coral reefs and the ocean food chains that depend upon them.The interactions are complex, although Kolbert does a masterful job of making them comprehensible, even to a non-scientist like me. Briefly, as carbon dioxide in the atmosphere rises, more is absorbed into the oceans. The dissolved carbon dioxide is making the oceans more acidic and binding to calcite and other minerals that are the basic building blocks for corals and other calcifying organisms (those that build shells or skeletons from calcium carbonate). "Imagine," Kolbert writes, "trying to build a house when someone keeps stealing your bricks."Kolbert's article is not available online and as of today is no longer in the bookstores. It's worth digging out from your pile of New Yorkers, borrowing from a friend, or even taking a trip to the library. These brief excerpts may persuade you:
Already humans have pumped enough carbon into the oceans--some hundred and twenty billion tons--to produce a .1 decline in surface pH. Since pH, like the Richter scale, is a logarithmic measure, a .1 drop represents a rise in acidity of about thirty percent…Coral reefs are under threat for a host of reasons: bottom trawling, dynamite fishing, coastal erosion, agricultural runoff, and, nowadays, global warming. When water temperatures rise too high, corals lose--or perhaps expel, no one is quite sure--the algae that nourish them. (The process is called "bleaching," because without their zooxanthellae corals appear white.) For a particular reef, any one of these threats could potentially be fatal. Ocean acidification poses a different kind of threat, one that could preclude the very possibility of a reef…The recent report on acidification by Britain's Royal Society noted that it was "not possible to predict" how whole communities would respond, but went on to observe that "without significant action to reduce CO2 emissions" there may be "no place in the future oceans for many of the species and ecosystems we know today."…Thomas Lovejoy, who coined the term "biological diversity" in 1980, compared the effects of ocean acidification to "running the course of evolution in reverse.""For an organism that lives on land, the two most important factors are temperature and moisture," Lovejoy, who is now the president of the Heinz Center for Science, Economics, and the Environment, in Washington, D.C., told me. "And for an organism that lives in the water the two most important factors are temperature and acidity. So this is just a profound, profound change… You could have food chains collapse, and fisheries ultimately with them, because most of the fish we get from the ocean are at the end of long food chains. You probably will see shifts in favor of invertebrates, or the reign of jellyfish."[Another scientist]…put it this way: "The risk is that at the end we will have the rise of slime."
William Cline, a joint fellow at CGD and the Peterson Institute for International Economics, and the author of the pioneering 1992 study, The Economics of Global Warming, is now at work on a new book that estimates the differential impact of global warming on agricultural production in the rich world and in developing countries. In it he argues that developing countries will pay a much higher price. For example, a warmer climate could boost wheat production in Canada and Siberia, but impede production of tropical crops in places that are already hot.To this grim calculus we should now add calculations on the differential impact of ocean acidification on rich and poor countries. A global collapse of reefs and fisheries would be bad news for everybody, but perhaps especially for the millions of very low-income people in the developing world who rely on coastal fisheries for much of their protein.The New Yorker article led me to search for other sources of information on this phenomenon. Remarkably, given the wealth of information and discussion on global warming, online information about ocean acidification was largely confined to scientific literature. See for example: AcidO ("An information outlet on Ocean Acidification"); and Cold Ocean Acidification which contains two startling maps of the depletion of available calcite by 2090 as a result the oceans' absorption of carbon dioxide.As with global warming, it's urgent that the policy community--and perhaps the development policy community in particular--start paying serious attention to what the scientists are telling us.


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